package iamutkarshtiwari.github.io.ananas.editimage.view.imagezoom;

import android.annotation.SuppressLint;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Matrix;
import android.graphics.PointF;
import android.graphics.RectF;
import android.graphics.drawable.Drawable;
import android.os.Handler;
import android.util.AttributeSet;
import android.util.Log;
import android.widget.ImageView;

import iamutkarshtiwari.github.io.ananas.editimage.view.imagezoom.easing.Cubic;
import iamutkarshtiwari.github.io.ananas.editimage.view.imagezoom.easing.Easing;
import iamutkarshtiwari.github.io.ananas.editimage.view.imagezoom.graphic.FastBitmapDrawable;
import iamutkarshtiwari.github.io.ananas.editimage.view.imagezoom.utils.IDisposable;


/**
 * Base View to manage image zoom/scrool/pinch operations
 * 
 * @author alessandro
 * 
 */
public abstract class ImageViewTouchBase extends ImageView implements
		IDisposable {

	public interface OnDrawableChangeListener {

		/**
		 * Callback invoked when a new drawable has been assigned to the view
		 * 
		 * @param drawable
		 */
		void onDrawableChanged(Drawable drawable);
	};

	public interface OnLayoutChangeListener {
		/**
		 * Callback invoked when the layout bounds changed
		 * 
		 * @param changed
		 * @param left
		 * @param top
		 * @param right
		 * @param bottom
		 */
		void onLayoutChanged(boolean changed, int left, int top, int right,
							 int bottom);
	};

	/**
	 * Use this to change the
	 * {@link ImageViewTouchBase#setDisplayType(DisplayType)} of this View
	 * 
	 * @author alessandro
	 * 
	 */
	public enum DisplayType {
		/** Image is not scaled by default */
		NONE,
		/** Image will be always presented using this view's bounds */
		FIT_TO_SCREEN,
		/** Image will be scaled only if bigger than the bounds of this view */
		FIT_IF_BIGGER
	};

	public static final String LOG_TAG = "ImageViewTouchBase";
	protected static final boolean LOG_ENABLED = false;

	public static final float ZOOM_INVALID = -1f;

	protected Easing mEasing = new Cubic();
	protected Matrix mBaseMatrix = new Matrix();
	protected Matrix mSuppMatrix = new Matrix();
	protected Matrix mNextMatrix;
	protected Handler mHandler = new Handler();
	protected Runnable mLayoutRunnable = null;
	protected boolean mUserScaled = false;

	private float mMaxZoom = ZOOM_INVALID;
	private float mMinZoom = ZOOM_INVALID;

	// true when min and max zoom are explicitly defined
	private boolean mMaxZoomDefined;
	private boolean mMinZoomDefined;

	protected final Matrix mDisplayMatrix = new Matrix();
	protected final float[] mMatrixValues = new float[9];

	private int mThisWidth = -1;
	private int mThisHeight = -1;
	private PointF mCenter = new PointF();

	protected DisplayType mScaleType = DisplayType.NONE;
	private boolean mScaleTypeChanged;
	private boolean mBitmapChanged;

	final protected int DEFAULT_ANIMATION_DURATION = 200;

	protected RectF mBitmapRect = new RectF();
	protected RectF mCenterRect = new RectF();
	protected RectF mScrollRect = new RectF();

	private OnDrawableChangeListener mDrawableChangeListener;
	private OnLayoutChangeListener mOnLayoutChangeListener;

	public ImageViewTouchBase(Context context) {
		super(context);
		init();
	}

	public ImageViewTouchBase(Context context, AttributeSet attrs) {
		super(context, attrs);
		init();
	}

	public void setOnDrawableChangedListener(OnDrawableChangeListener listener) {
		mDrawableChangeListener = listener;
	}

	public void setOnLayoutChangeListener(OnLayoutChangeListener listener) {
		mOnLayoutChangeListener = listener;
	}

	protected void init() {
		setScaleType(ScaleType.MATRIX);
	}

	@Override
	public void setScaleType(ScaleType scaleType) {
		if (scaleType == ScaleType.MATRIX) {
			super.setScaleType(scaleType);
		} else {
			Log.w(LOG_TAG, "Unsupported scaletype. Only MATRIX can be used");
		}
	}

	/**
	 * Clear the current drawable
	 */
	public void clear() {
		setImageBitmap(null);
	}

	/**
	 * Change the display type
	 */
	public void setDisplayType(DisplayType type) {
		if (type != mScaleType) {
			if (LOG_ENABLED) {
				Log.i(LOG_TAG, "setDisplayType: " + type);
			}
			mUserScaled = false;
			mScaleType = type;
			mScaleTypeChanged = true;
			requestLayout();
		}
	}

	public DisplayType getDisplayType() {
		return mScaleType;
	}

	protected void setMinScale(float value) {
		if (LOG_ENABLED) {
			Log.d(LOG_TAG, "setMinZoom: " + value);
		}

		mMinZoom = value;
	}

	protected void setMaxScale(float value) {
		if (LOG_ENABLED) {
			Log.d(LOG_TAG, "setMaxZoom: " + value);
		}
		mMaxZoom = value;
	}

	@Override
	protected void onLayout(boolean changed, int left, int top, int right,
			int bottom) {

		if (LOG_ENABLED) {
			Log.e(LOG_TAG, "onLayout: " + changed + ", bitmapChanged: "
					+ mBitmapChanged + ", scaleChanged: " + mScaleTypeChanged);
		}

		super.onLayout(changed, left, top, right, bottom);

		int deltaX = 0;
		int deltaY = 0;

		if (changed) {
			int oldw = mThisWidth;
			int oldh = mThisHeight;

			mThisWidth = right - left;
			mThisHeight = bottom - top;

			deltaX = mThisWidth - oldw;
			deltaY = mThisHeight - oldh;

			// update center point
			mCenter.x = mThisWidth / 2f;
			mCenter.y = mThisHeight / 2f;
		}

		Runnable r = mLayoutRunnable;

		if (r != null) {
			mLayoutRunnable = null;
			r.run();
		}

		final Drawable drawable = getDrawable();

		if (drawable != null) {

			if (changed || mScaleTypeChanged || mBitmapChanged) {

				float scale = 1;

				// retrieve the old values
				float old_default_scale = getDefaultScale(mScaleType);
				float old_matrix_scale = getScale(mBaseMatrix);
				float old_scale = getScale();
				float old_min_scale = Math.min(1f, 1f / old_matrix_scale);

				getProperBaseMatrix(drawable, mBaseMatrix);

				float new_matrix_scale = getScale(mBaseMatrix);

				if (LOG_ENABLED) {
					Log.d(LOG_TAG, "old matrix scale: " + old_matrix_scale);
					Log.d(LOG_TAG, "new matrix scale: " + new_matrix_scale);
					Log.d(LOG_TAG, "old min scale: " + old_min_scale);
					Log.d(LOG_TAG, "old scale: " + old_scale);
				}

				// 1. bitmap changed or scaletype changed
				if (mBitmapChanged || mScaleTypeChanged) {

					if (LOG_ENABLED) {
						Log.d(LOG_TAG, "display type: " + mScaleType);
					}

					if (mNextMatrix != null) {
						mSuppMatrix.set(mNextMatrix);
						mNextMatrix = null;
						scale = getScale();
					} else {
						mSuppMatrix.reset();
						scale = getDefaultScale(mScaleType);
					}

					setImageMatrix(getImageViewMatrix());

					if (scale != getScale()) {
						zoomTo(scale);
					}

				} else if (changed) {

					// 2. layout size changed

					if (!mMinZoomDefined)
						mMinZoom = ZOOM_INVALID;
					if (!mMaxZoomDefined)
						mMaxZoom = ZOOM_INVALID;

					setImageMatrix(getImageViewMatrix());
					postTranslate(-deltaX, -deltaY);

					if (!mUserScaled) {
						scale = getDefaultScale(mScaleType);
						zoomTo(scale);
					} else {
						if (Math.abs(old_scale - old_min_scale) > 0.001) {
							scale = (old_matrix_scale / new_matrix_scale)
									* old_scale;
						}
						zoomTo(scale);
					}

					if (LOG_ENABLED) {
						Log.d(LOG_TAG, "old min scale: " + old_default_scale);
						Log.d(LOG_TAG, "old scale: " + old_scale);
						Log.d(LOG_TAG, "new scale: " + scale);
					}

				}

				mUserScaled = false;

				if (scale > getMaxScale() || scale < getMinScale()) {
					// if current scale if outside the min/max bounds
					// then restore the correct scale
					zoomTo(scale);
				}

				center(true, true);

				if (mBitmapChanged)
					onDrawableChanged(drawable);
				if (changed || mBitmapChanged || mScaleTypeChanged)
					onLayoutChanged(left, top, right, bottom);

				if (mScaleTypeChanged)
					mScaleTypeChanged = false;
				if (mBitmapChanged)
					mBitmapChanged = false;

				if (LOG_ENABLED) {
					Log.d(LOG_TAG, "new scale: " + getScale());
				}
			}
		} else {
			// drawable is null
			if (mBitmapChanged)
				onDrawableChanged(drawable);
			if (changed || mBitmapChanged || mScaleTypeChanged)
				onLayoutChanged(left, top, right, bottom);

			if (mBitmapChanged)
				mBitmapChanged = false;
			if (mScaleTypeChanged)
				mScaleTypeChanged = false;

		}
	}

	/**
	 * Restore the original display
	 * 
	 */
	public void resetDisplay() {
		mBitmapChanged = true;
		requestLayout();
	}

	protected float getDefaultScale(DisplayType type) {
		if (type == DisplayType.FIT_TO_SCREEN) {
			// always fit to screen
			return 1f;
		} else if (type == DisplayType.FIT_IF_BIGGER) {
			// normal scale if smaller, fit to screen otherwise
			return Math.min(1f, 1f / getScale(mBaseMatrix));
		} else {
			// no scale
			return 1f / getScale(mBaseMatrix);
		}
	}

	@Override
	public void setImageResource(int resId) {
		setImageDrawable(getContext().getResources().getDrawable(resId));
	}

	/**
	 * {@inheritDoc} Set the new image to display and reset the internal matrix.
	 * 
	 * @param bitmap
	 *            the {@link Bitmap} to display
	 * @see {@link ImageView#setImageBitmap(Bitmap)}
	 */
	@Override
	public void setImageBitmap(final Bitmap bitmap) {
		setImageBitmap(bitmap, null, ZOOM_INVALID, ZOOM_INVALID);
	}

	/**
	 * @see #setImageDrawable(Drawable, Matrix, float, float)
	 * 
	 * @param bitmap
	 * @param matrix
	 * @param min_zoom
	 * @param max_zoom
	 */
	public void setImageBitmap(final Bitmap bitmap, Matrix matrix,
			float min_zoom, float max_zoom) {
		if (bitmap != null)
			setImageDrawable(new FastBitmapDrawable(bitmap), matrix, min_zoom,
					max_zoom);
		else
			setImageDrawable(null, matrix, min_zoom, max_zoom);
	}

	@Override
	public void setImageDrawable(Drawable drawable) {
		setImageDrawable(drawable, null, ZOOM_INVALID, ZOOM_INVALID);
	}

	/**
	 * 
	 * Note: if the scaleType is FitToScreen then min_zoom must be <= 1 and
	 * max_zoom must be >= 1
	 * 
	 * @param drawable
	 *            the new drawable
	 * @param initial_matrix
	 *            the optional initial display matrix
	 * @param min_zoom
	 *            the optional minimum scale, pass {@link #ZOOM_INVALID} to use
	 *            the default min_zoom
	 * @param max_zoom
	 *            the optional maximum scale, pass {@link #ZOOM_INVALID} to use
	 *            the default max_zoom
	 */
	public void setImageDrawable(final Drawable drawable,
			final Matrix initial_matrix, final float min_zoom,
			final float max_zoom) {

		final int viewWidth = getWidth();

		if (viewWidth <= 0) {
			mLayoutRunnable = new Runnable() {

				@Override
				public void run() {
					setImageDrawable(drawable, initial_matrix, min_zoom,
							max_zoom);
				}
			};
			return;
		}
		_setImageDrawable(drawable, initial_matrix, min_zoom, max_zoom);
	}

	protected void _setImageDrawable(final Drawable drawable,
			final Matrix initial_matrix, float min_zoom, float max_zoom) {

		if (LOG_ENABLED) {
			Log.i(LOG_TAG, "_setImageDrawable");
		}

		if (drawable != null) {

			if (LOG_ENABLED) {
				Log.d(LOG_TAG, "size: " + drawable.getIntrinsicWidth() + "x"
						+ drawable.getIntrinsicHeight());
			}
			super.setImageDrawable(drawable);
		} else {
			mBaseMatrix.reset();
			super.setImageDrawable(null);
		}

		if (min_zoom != ZOOM_INVALID && max_zoom != ZOOM_INVALID) {
			min_zoom = Math.min(min_zoom, max_zoom);
			max_zoom = Math.max(min_zoom, max_zoom);

			mMinZoom = min_zoom;
			mMaxZoom = max_zoom;

			mMinZoomDefined = true;
			mMaxZoomDefined = true;

			if (mScaleType == DisplayType.FIT_TO_SCREEN
					|| mScaleType == DisplayType.FIT_IF_BIGGER) {

				if (mMinZoom >= 1) {
					mMinZoomDefined = false;
					mMinZoom = ZOOM_INVALID;
				}

				if (mMaxZoom <= 1) {
					mMaxZoomDefined = true;
					mMaxZoom = ZOOM_INVALID;
				}
			}
		} else {
			mMinZoom = ZOOM_INVALID;
			mMaxZoom = ZOOM_INVALID;

			mMinZoomDefined = false;
			mMaxZoomDefined = false;
		}

		if (initial_matrix != null) {
			mNextMatrix = new Matrix(initial_matrix);
		}

		mBitmapChanged = true;
		requestLayout();
	}

	/**
	 * Fired as soon as a new Bitmap has been set
	 * 
	 * @param drawable
	 */
	protected void onDrawableChanged(final Drawable drawable) {
		if (LOG_ENABLED) {
			Log.i(LOG_TAG, "onDrawableChanged");
		}
		fireOnDrawableChangeListener(drawable);
	}

	protected void fireOnLayoutChangeListener(int left, int top, int right,
			int bottom) {
		if (null != mOnLayoutChangeListener) {
			mOnLayoutChangeListener.onLayoutChanged(true, left, top, right,
					bottom);
		}
	}

	protected void fireOnDrawableChangeListener(Drawable drawable) {
		if (null != mDrawableChangeListener) {
			mDrawableChangeListener.onDrawableChanged(drawable);
		}
	}

	/**
	 * Called just after {@link #onLayout(boolean, int, int, int, int)} if the
	 * view's bounds has changed or a new Drawable has been set or the
	 * {@link DisplayType} has been modified
	 * 
	 * @param left
	 * @param top
	 * @param right
	 * @param bottom
	 */
	protected void onLayoutChanged(int left, int top, int right, int bottom) {
		if (LOG_ENABLED) {
			Log.i(LOG_TAG, "onLayoutChanged");
		}
		fireOnLayoutChangeListener(left, top, right, bottom);
	}

	protected float computeMaxZoom() {
		final Drawable drawable = getDrawable();

		if (drawable == null) {
			return 1F;
		}

		float fw = (float) drawable.getIntrinsicWidth() / (float) mThisWidth;
		float fh = (float) drawable.getIntrinsicHeight() / (float) mThisHeight;
		float scale = Math.max(fw, fh) * 8;

		if (LOG_ENABLED) {
			Log.i(LOG_TAG, "computeMaxZoom: " + scale);
		}
		return scale;
	}

	protected float computeMinZoom() {
		final Drawable drawable = getDrawable();

		if (drawable == null) {
			return 1F;
		}

		float scale = getScale(mBaseMatrix);
		scale = Math.min(1f, 1f / scale);

		if (LOG_ENABLED) {
			Log.i(LOG_TAG, "computeMinZoom: " + scale);
		}

		return scale;
	}

	/**
	 * Returns the current maximum allowed image scale
	 * 
	 * @return
	 */
	public float getMaxScale() {
		if (mMaxZoom == ZOOM_INVALID) {
			mMaxZoom = computeMaxZoom();
		}
		return mMaxZoom;
	}

	/**
	 * Returns the current minimum allowed image scale
	 * 
	 * @return
	 */
	public float getMinScale() {
		if (mMinZoom == ZOOM_INVALID) {
			mMinZoom = computeMinZoom();
		}
		return mMinZoom;
	}

	/**
	 * Returns the current view matrix
	 * 
	 * @return
	 */
	public Matrix getImageViewMatrix() {
		return getImageViewMatrix(mSuppMatrix);
	}

	public Matrix getImageViewMatrix(Matrix supportMatrix) {
		mDisplayMatrix.set(mBaseMatrix);
		mDisplayMatrix.postConcat(supportMatrix);
		return mDisplayMatrix;
	}

	@Override
	public void setImageMatrix(Matrix matrix) {

		Matrix current = getImageMatrix();
		boolean needUpdate = false;

		if (matrix == null && !current.isIdentity() || matrix != null
				&& !current.equals(matrix)) {
			needUpdate = true;
		}

		super.setImageMatrix(matrix);

		if (needUpdate)
			onImageMatrixChanged();
	}

	/**
	 * Called just after a new Matrix has been assigned.
	 * 
	 * @see {@link #setImageMatrix(Matrix)}
	 */
	protected void onImageMatrixChanged() {
	}

	/**
	 * Returns the current image display matrix.<br />
	 * This matrix can be used in the next call to the
	 * {@link #setImageDrawable(Drawable, Matrix, float, float)} to restore the
	 * same view state of the previous {@link Bitmap}.<br />
	 * Example:
	 * 
	 * <pre>
	 * Matrix currentMatrix = mImageView.getDisplayMatrix();
	 * mImageView.setImageBitmap(newBitmap, currentMatrix, ZOOM_INVALID, ZOOM_INVALID);
	 * </pre>
	 * 
	 * @return the current support matrix
	 */
	public Matrix getDisplayMatrix() {
		return new Matrix(mSuppMatrix);
	}

	/**
	 * Setup the base matrix so that the image is centered and scaled properly.
	 * 
	 * @param drawable
	 * @param matrix
	 */
	protected void getProperBaseMatrix(Drawable drawable, Matrix matrix) {
		float viewWidth = mThisWidth;
		float viewHeight = mThisHeight;

		if (LOG_ENABLED) {
			Log.d(LOG_TAG, "getProperBaseMatrix. view: " + viewWidth + "x"
					+ viewHeight);
		}

		float w = drawable.getIntrinsicWidth();
		float h = drawable.getIntrinsicHeight();
		float widthScale, heightScale;
		matrix.reset();

		if (w > viewWidth || h > viewHeight) {
			widthScale = viewWidth / w;
			heightScale = viewHeight / h;
			float scale = Math.min(widthScale, heightScale);
			matrix.postScale(scale, scale);

			float tw = (viewWidth - w * scale) / 2.0f;
			float th = (viewHeight - h * scale) / 2.0f;
			matrix.postTranslate(tw, th);

		} else {
			widthScale = viewWidth / w;
			heightScale = viewHeight / h;
			float scale = Math.min(widthScale, heightScale);
			matrix.postScale(scale, scale);

			float tw = (viewWidth - w * scale) / 2.0f;
			float th = (viewHeight - h * scale) / 2.0f;
			matrix.postTranslate(tw, th);
		}

		if (LOG_ENABLED) {
			printMatrix(matrix);
		}
	}

	/**
	 * Setup the base matrix so that the image is centered and scaled properly.
	 * 
	 * @param bitmap
	 * @param matrix
	 */
	protected void getProperBaseMatrix2(Drawable bitmap, Matrix matrix) {

		float viewWidth = mThisWidth;
		float viewHeight = mThisHeight;

		float w = bitmap.getIntrinsicWidth();
		float h = bitmap.getIntrinsicHeight();

		matrix.reset();

		float widthScale = viewWidth / w;
		float heightScale = viewHeight / h;

		float scale = Math.min(widthScale, heightScale);

		matrix.postScale(scale, scale);
		matrix.postTranslate((viewWidth - w * scale) / 2.0f, (viewHeight - h
				* scale) / 2.0f);
	}

	protected float getValue(Matrix matrix, int whichValue) {
		matrix.getValues(mMatrixValues);
		return mMatrixValues[whichValue];
	}

	public void printMatrix(Matrix matrix) {
		float scalex = getValue(matrix, Matrix.MSCALE_X);
		float scaley = getValue(matrix, Matrix.MSCALE_Y);
		float tx = getValue(matrix, Matrix.MTRANS_X);
		float ty = getValue(matrix, Matrix.MTRANS_Y);
		Log.d(LOG_TAG, "matrix: { x: " + tx + ", y: " + ty + ", scalex: "
				+ scalex + ", scaley: " + scaley + " }");
	}

	public RectF getBitmapRect() {
		return getBitmapRect(mSuppMatrix);
	}

	protected RectF getBitmapRect(Matrix supportMatrix) {
		final Drawable drawable = getDrawable();

		if (drawable == null)
			return null;
		Matrix m = getImageViewMatrix(supportMatrix);
		mBitmapRect.set(0, 0, drawable.getIntrinsicWidth(),
				drawable.getIntrinsicHeight());
		m.mapRect(mBitmapRect);
		return mBitmapRect;
	}

	protected float getScale(Matrix matrix) {
		return getValue(matrix, Matrix.MSCALE_X);
	}

	@SuppressLint("Override")
	public float getRotation() {
		return 0;
	}

	/**
	 * Returns the current image scale
	 * 
	 * @return
	 */
	public float getScale() {
		return getScale(mSuppMatrix);
	}

	protected void center(boolean horizontal, boolean vertical) {
		final Drawable drawable = getDrawable();
		if (drawable == null)
			return;

		RectF rect = getCenter(mSuppMatrix, horizontal, vertical);

		if (rect.left != 0 || rect.top != 0) {

			if (LOG_ENABLED) {
				Log.i(LOG_TAG, "center");
			}
			postTranslate(rect.left, rect.top);
		}
	}

	protected RectF getCenter(Matrix supportMatrix, boolean horizontal,
			boolean vertical) {
		final Drawable drawable = getDrawable();

		if (drawable == null)
			return new RectF(0, 0, 0, 0);

		mCenterRect.set(0, 0, 0, 0);
		RectF rect = getBitmapRect(supportMatrix);
		float height = rect.height();
		float width = rect.width();
		float deltaX = 0, deltaY = 0;
		if (vertical) {
			int viewHeight = mThisHeight;
			if (height < viewHeight) {
				deltaY = (viewHeight - height) / 2 - rect.top;
			} else if (rect.top > 0) {
				deltaY = -rect.top;
			} else if (rect.bottom < viewHeight) {
				deltaY = mThisHeight - rect.bottom;
			}
		}
		if (horizontal) {
			int viewWidth = mThisWidth;
			if (width < viewWidth) {
				deltaX = (viewWidth - width) / 2 - rect.left;
			} else if (rect.left > 0) {
				deltaX = -rect.left;
			} else if (rect.right < viewWidth) {
				deltaX = viewWidth - rect.right;
			}
		}
		mCenterRect.set(deltaX, deltaY, 0, 0);
		return mCenterRect;
	}

	protected void postTranslate(float deltaX, float deltaY) {
		if (deltaX != 0 || deltaY != 0) {
			if (LOG_ENABLED) {
				Log.i(LOG_TAG, "postTranslate: " + deltaX + "x" + deltaY);
			}
			mSuppMatrix.postTranslate(deltaX, deltaY);
			setImageMatrix(getImageViewMatrix());
		}
	}

	protected void postScale(float scale, float centerX, float centerY) {
		if (LOG_ENABLED) {
			Log.i(LOG_TAG, "postScale: " + scale + ", center: " + centerX + "x"
					+ centerY);
		}
		mSuppMatrix.postScale(scale, scale, centerX, centerY);
		setImageMatrix(getImageViewMatrix());
	}

	protected PointF getCenter() {
		return mCenter;
	}

	protected void zoomTo(float scale) {
		if (scale > getMaxScale())
			scale = getMaxScale();
		if (scale < getMinScale())
			scale = getMinScale();

		PointF center = getCenter();
		zoomTo(scale, center.x, center.y);
	}

	/**
	 * Scale to the target scale
	 * 
	 * @param scale
	 *            the target zoom
	 * @param durationMs
	 *            the animation duration
	 */
	public void zoomTo(float scale, float durationMs) {
		PointF center = getCenter();
		zoomTo(scale, center.x, center.y, durationMs);
	}

	protected void zoomTo(float scale, float centerX, float centerY) {
		if (scale > getMaxScale())
			scale = getMaxScale();

		float oldScale = getScale();
		float deltaScale = scale / oldScale;
		postScale(deltaScale, centerX, centerY);
		onZoom(getScale());
		center(true, true);
	}

	protected void onZoom(float scale) {
	}

	protected void onZoomAnimationCompleted(float scale) {
	}

	/**
	 * Scrolls the view by the x and y amount
	 * 
	 * @param x
	 * @param y
	 */
	public void scrollBy(float x, float y) {
		panBy(x, y);
	}

	protected void panBy(double dx, double dy) {
		RectF rect = getBitmapRect();
		mScrollRect.set((float) dx, (float) dy, 0, 0);
		updateRect(rect, mScrollRect);
		postTranslate(mScrollRect.left, mScrollRect.top);
		center(true, true);
	}

	protected void updateRect(RectF bitmapRect, RectF scrollRect) {
		if (bitmapRect == null)
			return;

		if (bitmapRect.top >= 0 && bitmapRect.bottom <= mThisHeight)
			scrollRect.top = 0;
		if (bitmapRect.left >= 0 && bitmapRect.right <= mThisWidth)
			scrollRect.left = 0;
		if (bitmapRect.top + scrollRect.top >= 0
				&& bitmapRect.bottom > mThisHeight)
			scrollRect.top = (int) (0 - bitmapRect.top);
		if (bitmapRect.bottom + scrollRect.top <= (mThisHeight - 0)
				&& bitmapRect.top < 0)
			scrollRect.top = (int) ((mThisHeight - 0) - bitmapRect.bottom);
		if (bitmapRect.left + scrollRect.left >= 0)
			scrollRect.left = (int) (0 - bitmapRect.left);
		if (bitmapRect.right + scrollRect.left <= (mThisWidth - 0))
			scrollRect.left = (int) ((mThisWidth - 0) - bitmapRect.right);
	}

	protected void scrollBy(float distanceX, float distanceY,
			final double durationMs) {
		final double dx = distanceX;
		final double dy = distanceY;
		final long startTime = System.currentTimeMillis();
		mHandler.post(new Runnable() {

			double old_x = 0;
			double old_y = 0;

			@Override
			public void run() {
				long now = System.currentTimeMillis();
				double currentMs = Math.min(durationMs, now - startTime);
				double x = mEasing.easeOut(currentMs, 0, dx, durationMs);
				double y = mEasing.easeOut(currentMs, 0, dy, durationMs);
				panBy((x - old_x), (y - old_y));
				old_x = x;
				old_y = y;
				if (currentMs < durationMs) {
					mHandler.post(this);
				} else {
					RectF centerRect = getCenter(mSuppMatrix, true, true);
					if (centerRect.left != 0 || centerRect.top != 0)
						scrollBy(centerRect.left, centerRect.top);
				}
			}
		});
	}

	protected void zoomTo(float scale, float centerX, float centerY,
			final float durationMs) {
		if (scale > getMaxScale())
			scale = getMaxScale();

		final long startTime = System.currentTimeMillis();
		final float oldScale = getScale();

		final float deltaScale = scale - oldScale;

		Matrix m = new Matrix(mSuppMatrix);
		m.postScale(scale, scale, centerX, centerY);
		RectF rect = getCenter(m, true, true);

		final float destX = centerX + rect.left * scale;
		final float destY = centerY + rect.top * scale;

		mHandler.post(new Runnable() {

			@Override
			public void run() {
				long now = System.currentTimeMillis();
				float currentMs = Math.min(durationMs, now - startTime);
				float newScale = (float) mEasing.easeInOut(currentMs, 0,
						deltaScale, durationMs);
				zoomTo(oldScale + newScale, destX, destY);
				if (currentMs < durationMs) {
					mHandler.post(this);
				} else {
					onZoomAnimationCompleted(getScale());
					center(true, true);
				}
			}
		});
	}

	@Override
	public void dispose() {
		clear();
	}
}
